Swift Onset, Swift Recovery: Unusual Nonrheumatic Myocarditis in a Young Adult Post Group A Streptococcal Pharyngitis

This case report highlights the unusual presentation and management of nonrheumatic myocarditis in a 24-year-old male, an age demographic not commonly associated with myocardial complications following Group A streptococcal pharyngitis. The patient, devoid of any prior medical history, manifested symptoms one day after being diagnosed with Group A streptococcal pharyngitis, a stark contrast to the typical progression of myocardial complications. The swift onset of symptoms and the patient's subsequent clinical presentation necessitated a comprehensive diagnostic approach. The patient's symptoms were successfully alleviated with amoxicillin and anti-inflammatory therapy, underscoring its potential efficacy in managing nonrheumatic myocarditis. This case serves as a poignant reminder of the importance of maintaining a broad differential diagnosis, especially in atypical presentations, and the pivotal role of timely clinical intervention. The insights from this report contribute to the broader understanding of nonrheumatic myocarditis, emphasizing the significance of tailored diagnostic and therapeutic strategies to ensure optimal patient outcomes.


Introduction
Nonrheumatic myocarditis (NRM) is a distinct clinical entity that stands apart from the more commonly recognized acute rheumatic fever (ARF) [1].Unlike ARF, which typically presents weeks after a Group A streptococcal (GAS) infection, NRM makes its appearance in a much shorter timeframe.Tis rapid onset of symptoms, coupled with its clinical manifestations, can often lead to diagnostic challenges [2].ECG changes, particularly ST elevations, further complicate the clinical picture, making it imperative for clinicians to diferentiate between an actual myocardial infarction and NRM [2].Te diferentiation is crucial, as the management strategies for both conditions difer signifcantly.While the pathophysiology of ARF is better understood, involving molecular mimicry that triggers crossreactive immune responses between host cardiac antigens and Streptococcus antigens, the pathophysiology of NRM is less understood and is thought to arise from direct invasion of the myocardium by the GAS organism or through a toxinmediated mechanism [1,3].In contrast to a toxin-mediated pathophysiology, a recent article found that bacteria, neutrophilic infltrate, and microabscesses were found on histological examination of a patient with recurrent myocarditis on autopsy [4].Given these diverging conclusions, current literature on the pathophysiology of NRM is poorly understood and therefore further warrants future research to be done [5].Tis diference in pathogenesis further underscores the need for a precise diagnosis.
While the immediate treatment might appear similar, the long-term management and follow-up vary [2].Recent case reports generally indicate that treatment aimed at addressing Streptococcal infection also serves as the primary approach for nonrheumatic myocarditis, often resulting in resolution of symptoms within a few days to one week [6,7].Tis suggests that treatment typically includes antibiotics like penicillin, supplemented occasionally by supportive care such as rest, NSAIDs, and colchicine, which have been endorsed as benefcial management options [6,8].Additionally, the rarity of NRM in developed nations often leads to a lower index of suspicion among healthcare providers [2].However, given the potential severity of the condition and its implications, a heightened awareness and understanding of NRM are essential.Tis case of a 24-year-old male emphasizes the importance of considering NRM in the diferential diagnosis when young adults present with cardiac symptoms following a GAS infection [2].

Case Presentation
Te patient is a 24-year-old male with no previous medical history who presented to an urgent care clinic with nonradiating central chest pain onset of a few hours.One day prior, the patient was evaluated at a family medicine clinic for a sore throat where rapid antigen testing was positive for GAS pharyngitis for which he was prescribed amoxicillin 500 mg PO q12 h for 10 days.Vitals at that time were signifcant only for tachycardia with a heart rate of 116 beats per minute.On arrival to the urgent care, an ECG was performed showing sinus bradycardia with T wave inversions in leads III, aVR, V1, and V2 and ST depressions in leads aVR and V1 can be seen in Figure 1.Subsequently, the patient was escorted to the emergency room (ER) for further evaluation.
In the ER, vital signs again revealed bradycardia, but were otherwise unremarkable.Patient received a one-time dose of aspirin 324 mg PO.Labs were obtained and pertinent results are present in Table 1.
Due to the elevated troponin T value, the patient was started on a heparin drip and cardiology was consulted.Based on their evaluation, it was felt that the patient most likely had myocarditis and less likely acute coronary syndrome.A transthoracic echocardiogram was signifcant only for trace tricuspid and mitral regurgitation.Additionally, Cardiology reported that ECGs obtained during urgent care and ER could be a normal variant given that repeat ECGs continued to show the same fndings.No ECG demonstrated any evidence of acute coronary syndrome.
Te infectious diseases team was consulted for evaluation and treatment recommendations as well.Based on their evaluation and timing of chest pain just one day after the diagnosis of streptococcal pharyngitis, it was felt that the patient was likely experiencing nonrheumatic myocarditis rather than acute rheumatic fever, although concurrent viral myocarditis was thought to be a possibility.Te patient was initially treated with penicillin G IV 24 MU q24 h for GAS coverage and clindamycin 600 mg PO q12 h to decrease toxin production.Serological studies were ordered for adenovirus, CMV, EBV, echovirus (9,11,30), HHV 6 and 8, parvovirus B19, and a respiratory viral panel by PCR.Given clinical improvement over the following two days, the patient was prescribed indomethacin 25 mg TID, colchicine 0.6 mg BID, and amoxicillin 875 mg BID for 5, 7, and 10 days, respectively.
At follow up visits with family medicine and cardiology, symptoms had resolved completely.Echo viral 4, 7, 9, 11, and 30 antibodies were detected in serum during patient's admission into the hospital; however, subsequent convalescent titers were not performed given the patient's symptomatic improvement with antibiotics and antiinfammatory medications.No long-term pharmacological prophylaxis was indicated at this time due to complete resolution of symptoms.Nonpharmacological treatments included rest and limited physical activity for a few months with slow return to baseline as tolerated.Prognosis included a return to baseline with no future complications.After a year of follow-up appointments, the patient was medically cleared and follow ups were no longer scheduled.

Discussion
Tis case brings forth several considerations in the clinical approach and management of NRM, especially in atypical presentations.Te patient's experience underscores the importance of considering NRM and its complications in adult populations.

Diagnostic Distinctions between ARF and Nonrheumatic
Myocarditis.Te diagnostic criteria for ARF and NRM difer signifcantly, particularly in the context of a recent GAS infection.While ARF typically presents 2 to 3 weeks post-GAS infection, nonrheumatic myocarditis can manifest symptoms in a much shorter timeline [2].Laboratory fndings, such as elevated troponin levels, and specifc EKG readings, including ST-segment elevation, are more indicative of nonrheumatic myocarditis [9].In fact, a study found that cardiac troponin T (cTnT) levels typically remained within normal ranges in patients with acute rheumatic carditis, suggesting that cTnT might not be the most reliable diagnostic marker for ARF [10].Conversely, other cases discussing the instance of nonrheumatic streptococcal myocarditis presented with progressively rising troponin levels [11,12].Tese distinctions are crucial in the diagnostic setting, as they guide clinicians in diferentiating between these two conditions, which, although related to GAS infection, require diferent therapeutic approaches.

Underrepresentation in Young
Individuals.One of the major defning factors in this case is the patient's age.Te presentation in a 24-year-old male highlights the necessity for healthcare providers to maintain a high index of suspicion for GAS infection complications across a broader age range.Young individuals presenting with chest pain following a strep infection are often not immediately considered for nonrheumatic myocarditis.Te prevailing clinical perception leans towards ARF, especially given its historical association with GAS infections [13].However, nonrheumatic myocarditis can mimic STEMI presentations in young adults, emphasizing the need for heightened clinical suspicion [2].

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Case Reports in Infectious Diseases

Te Imperative of Recognizing Nonrheumatic
Myocarditis.Despite its rarity, NRM post-GAS infection should be a more prominent diferential in patients presenting with the aforementioned symptoms.Tis case and multiple others emphasize the importance of distinguishing between ARF and NRM, especially given the potential cardiac complications associated with the latter [13][14][15][16][17].A noteworthy point of mention is that titers were positive for echovirus 4, 7, 9, 11, and 30.Tese titers were deemed necessary to rule out their role on this patient.Nonetheless, successive titers were not performed due to the pathology resolution when treated with antibiotics and antiinfammatories.Furthermore, there have been documented instances where nonrheumatic myocarditis poststreptococcal pharyngitis presented as acute STelevation myocardial infarction, further emphasizing the clinical signifcance of this diferential [9,11,12,18,19].Furthermore, a systematic review of 70 patient studies revealed that approximately half (47.1%) of the patients exhibited ST-segment elevations, with the majority showing other notable EKG abnormalities as well [20].Interestingly, unlike those cases, which often exhibited ECG patterns resembling acute ST elevated myocardial infarctions, this particular case showed elevated troponin levels alongside a normal ECG reading (due to cardiologist normal variant fndings).Terefore, while this case shares similarities with others involving NRM, it stands out due to its clinical presentation with a normal ECG reading.

Conclusion
In conclusion, while ARF remains a signifcant concern post-GAS infection, the potential for nonrheumatic myocarditis should not be overlooked, especially in young individuals presenting with chest pain.Te diagnostic distinctions between these conditions, coupled with the underrepresentation of nonrheumatic myocarditis in clinical settings, underscore the importance of maintaining a broad diferential diagnosis.As the literature suggests, a more inclusive approach can lead to timely and appropriate interventions, ultimately improving patient outcomes.

Figure 1 :
Figure 1: ECG Normal vs. Patient.Patient's ECG demonstrated sinus bradycardia with T wave inversions in leads III, aVR, V1, and V2.Moderate ST depressions were noted in aVR and V1.No progression was noted over time which cardiologist mentioned could be a normal variant of the patient.